views: Make the radio or check in MenuItemView clickable.

Make the menu item handle click events on its icon view.
(support clicking on a radio/check icon in a menu item)

Bug: 768449
Test: See bug.
Change-Id: I1da3ce9baad36b1e35278e3a7c466e96c4e00876
Reviewed-on: https://chromium-review.googlesource.com/691175Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505402}

ui/views/controls/menu/menu_item_view.cc

@@ -696,6 +696,7 @@ void MenuItemView::Init(MenuItemView* parent,
         type_ == RADIO ||
         (type_ == CHECKBOX && GetDelegate()->IsItemChecked(GetCommand()));
     radio_check_image_view_->SetVisible(show_check_radio_icon);
+    radio_check_image_view_->set_can_process_events_within_subtree(false);
     AddChildView(radio_check_image_view_);
   }